gistfile1.php

<?php
require_once __DIR__ . '/app/code/local/Nivea/Mobile/Model/Device/Detect.php';
 
$mobile = new Nivea_Mobile_Model_Device_Detect();
$isMobile = $mobile->isMobile();

$currentUrl = $env = ($_SERVER['HTTP_HOST']) ? $_SERVER['HTTP_HOST'] : $_SERVER['SERVER_NAME'];
$scheme = isset($_SERVER['HTTPS']) ? 'https://' : 'http://';

if ($isMobile && $currentUrl ==  'shop.nivea.co.uk') {
    $url = $scheme . "mobileshop.nivea.co.uk";
    header("Location: $url");
    exit;
} 

if(!$isMobile && $currentUrl === 'mobileshop.nivea.co.uk') {
    $url = $scheme . "shop.nivea.co.uk";
    header("Location: $url");
    exit;
}

require_once __DIR__ . '/index.php';